The principal area of research will be the application of the technique of sedimentation equilibrium in density gradients in the analytical ultracentrifuge to the study of the physical-chemical properties of proteins. Proteins, synthetic polypeptides, and a number of their chemical derivatives will be banded in CsCl and other salt gradients as a function of pH employing standard techniques which have been developed in our laboratories. Correlative studies employing potentiometric titrimetry, spectropolarimetry, electrophoresis and osmometry will be conducted. Taken together, these data provide fundamental information about the ion-binding, numbers of ionizable residues and their pK values and the correlation of amino acid composition with the buoyant density of proteins. The partial specific volumes of a number of proteins and polypeptides will be measured in buoyant CsCl solutions as a function of pH. The new Anton Paar densimeter will be employed to rapidly and accurately determine solution density as a function of concentration. The same technique will be employed to determine the partial specific volume of water and the specific volume of poly(Lys) and poly(His) in these solutions. These data will then be combined with the buoyant densities of these polymers which have already been measured in order to obtain accurate hydration values without any assumptions for the first time.